Aircraft safety is an ongoing concern for aircraft producers. An unknown loose object on board an aircraft may cause an aircraft to malfunction or not operate as designed thereby decreasing safety of the aircraft. Unknown loose objects are referred to as foreign object debris (FOD) in the art. FOD are difficult to detect and many hours of searching for FOD occur during production of an aircraft, to assure the aircraft is free from loose objects, before the aircraft leaves a production facility or is operated. Moreover, because the detection of FOD relies almost solely on visual inspection, it can be subject to human error. Furthermore, confined nature of an aircraft structure hinders vehicle through inspection.
FOD are of various size and shape and can go undetected in large aircraft. A large aircraft has various cavities, pockets, and crevices that cause the process of detecting FOD to be difficult. For example, a small FOD item, such as a rivet or nut, lying in a dark crevice may go undetected during the search of a large aircraft. The larger the amount of undetected FOD the increased likelihood of an aircraft system malfunctioning.
A current method exists for locating a component that requires a supplemental restraining device on a portion of a gas turbine engine, as described in Garrity U.S. Pat. No. 6,150,656 entitled “Method of Assembly and Inspection for a Gas Turbine Engine”, hereinafter referred to as Garrity. In Garrity a fluorescent material is applied to components of a gas turbine engine that require a supplemental restraining device before assembly thereof. An electromagnetic radiation is directed at the gas turbine engine to illuminate the fluorescent material. Upon illumination of the fluorescent material, a confirmation is made as to whether the components that requires a supplemental restraining device do in fact have a supplemental restraining device properly installed. As known in the art and as taught by Garrity, in order to properly install a supplemental restraining device, such as a lock-wire, to a component, the component must be fixed, otherwise the supplemental restraining device does not serve its intended purpose. Garrity unfortunately, is only directed at fixed components, on a gas turbine engine, that require proper installation of a supplemental restraining device as to prevent the components from becoming unfastened.
One known method of detecting foreign object debris is described in Wagoner et al., U.S. patent application entitled “A Method for Detecting Foreign Object Debris”, hereinafter referred to as Wagoner. Wagoner teaches a method of detecting a non-fixed object, such as a loose fastener, within an aircraft. A light emitting substance is applied to the non-fixed object. A non-fixed object illuminator is used to illuminate the light emitting substance. The non-fixed object is detected due to the wavelength-specific light generated from illumination of the light emitting substance. Upon detection of the non-fixed object, the object is fastened or is determined to be FOD and is removed from the aircraft.
There are associated disadvantages with known FOD detecting methods. One disadvantage is that during inspection of an aircraft for FOD, using the known FOD detecting methods, some inspection areas can exist that are difficult to access or view and in some situations at least to some extent can not be inspected. Another disadvantage with exiting methods is that by continuously detecting FOD using an ultraviolet light source, eyestrain or ocular fluorescence can result that can lower a users ability to detect FOD. Furthermore, use of an ultraviolet lamp can be hazardous when there are defects in filters of existing FOD detecting systems that are used to eliminate more harmful ultraviolet wavelengths. Yet another disadvantage is that the existing systems use ultraviolet lamps that are large and can consume approximately 100 watts of power, thus generating a heat load and a potential burn or fire hazard.
There is a current desire to increase ability to detect FOD in a more effective and efficient manner than that used in Wagoner. It would therefore be desirable to develop an improved method for detecting FOD that reduces the time and costs involved in manufacturing of an aircraft which does not have the above-mentioned disadvantages with known existing techniques.